Electeic



JuneS, 1928. 1,672,223

J. KARCEVSK ELECTRI C HAMMER Filed April 25, 1927 Patented i 5 UNITED] .STATES PATENT, oFFlcE.

This invention relatesto improvements in electric hammers'and it consists of the matters hereinafter described and more particularly pointed out in the appended claims.

The'improved hammer is of the motor driven type and includes a reciprocating member receiving its power stroke from a spring and its return or liftingv stroke tllrough the action of a motor driven cam s a t.

One of the objects of the present invention is to provide a hammer of this kind wherein the reciprocating member may be temporarily disconnected from the motor driven shaft whereby the motor is relieved from a load during the starting thereof, and which member may be operatively connected to said shaft, afterthe motor is in operation.

A further object of the invention is to provide in connection with the driving motor, a fly or balance wheel which improves the operation of the motor and permits the use of asmaller motor and a small over all dimension for the hammer as a whole.

Still another object of the invention is to provide a hammer of this kind wherein the weight is more evenl distributed and a better balance provi ed therefor which relieves the operator from a considerable strain while using the hammer.

' A still further object of the invention is to provide a hammer of this kind which though ight in weight is powerful in operation and is capable of striking harder and more effective blows which is desirable in drill ing in concrete and the like.

Fig. 4 is a detail view in side elevation of a art of the hammer and which will be more fisly referred to later. Referring now in detail to that embodiment of the invention illustrated in the accompanying drawing, 1 indicates as a whole the casing for my improved hammer which includes an annular head 2 and a radially disposed tubular extension or barrel 3. The

head 2 is defined by an annular flange 4 divided intermediate its ends by a partition or wall 5, thus leaving said head open at its front and rear. In said annular flange 4 in front of-the wall 5 is an opening 6 communicating with the interior of the barrel 3. Coaxially with the wall 5 is a rearwardly extending bearing boss 7 the purpose of which will later appear and on the flange 4 directly opposite the tubular extension 3 is a closed grip handle 8 to be grasped in manipulating the hammer. The open front: end of the annular head is closed by a front plate 9, whilethe open rear end of said head is closed by the casing of an electric motor 10. I- find one convenient way to hold said parts together is to provide bolts 11-11 which extend through the motor casing from the rear and which pass through bosses 12-12 on the flange 4 to be screwed into the front plate all as best shown in Fig. 3. The front plate 9 is provided with a bearing boss 13 in line with the like boss 7 before mentioned. 14 indicates the armature shaft of the motor 10 which shaft has bearing in the sleeve 7. The forward end of this shaft is reduced in diameter as at 14 and on said end part of reduced diameter is a sleeve 15.,

carrying a cam 16. Said sleeve 15. is journalled in the boss 13 of the front plate and mounted on said sleeve outside of the front plate is the hub of a balance wheel 17, a pin 17 passing through said hub,

sleeve and shaft part 1d of reduced diameter.

The balance wheel 17 is of a diameter a proximating that of the casing head and its action permits the -"use of a smaller size motor. While the shaft-14 in this instance has been described as the armature shaft, this is to be considered as by we of illustration only because it may be a s aft other than an armature shaftand still be driven by it through suitable gearing or the like. The construction just described provides a good bearing for the shaft 14 and reduces the axial dimensions of the head of the hammer and permits a quick disassembly for inspection and cleaning.

On the front face of the wall 5 is provided spaced guide plates or ways 18 in which the cross head 19 of a reciprocating member 20 has sliding guiding hearing. In said cross head is provided a longitudinal slot .21 to. ac-

commodate the shaft 14. On the cross head just above the slot 21 is journalled a roller 22 adapted in the rotation of the shaft 1 to be engaged by the cam 16 to impart the return or lifting stroke to the reciprocating member. The cross head has a top extension 23 which includes, a forwardly extending stud or pin 24. The reciprocating member 20 extends through the opening 6 into the tubular barrel 3 where it is suitably fixed to a hammer head or impact member 25 which has sliding guiding bearing in the tubular barrel 3. In said head are provided two longitudinal openings 25 through which air in advance of the hammer may escape from the barrel. A helical expansion spring 26 surrounds the reciprocating member 20, between the impact member or hammer 25 and that part of the flange a defining the opening 6. @n the return or lifting stroke of the reciprocating member 20 under the action of the cam on the shaft 14, the spring is compressed and placed under tension and so soon as the cam sweeps past the roller 22, the spring acts to impose the power stroke on said reciprocating member.

ln the open end of the tubular extension or barrel 3 is threaded av tubular plug 27, the extreme free end of which is made hexagonal as shown in Fig.2 for the application of a wrench. Said plug has an axially disposed bore 27 in which the shank 28 of the tool 29 has bearing, said shank projecting a sufiicient distance beyond the inner end of said plug to be engaged by the impact member 25. (in said tool below or beyond the plug 27 is formed an annular shoulder 30 to be engaged by a part of a tool retainer 31, the same including laterally spaced yielding arms 32 each pivoted at its free end to the barrel as at 33. This, con-.

nection of said arms permits the retainer to be swung away from the shoulder 30 when so desired, for the easy removal and replace ment of the tool.

Means are provided to remove the reciprocating member from the influence of the cam on the shaft is so that the motor may be started without the load or resistance of said member, after which said member may be broughtinto position with respect to the cam so that it may operate for its intended purpose. l have found one convenient and simple means for such purpose to be as follows: @n the rear or inner face of the cover plate 9 l pivot as at 35, a cam 36 which includes a lever 37 extending out= weirdly through a suitable slot 38 in the cas ing flange l. At each end of the slot is pro vided a shoulder 39-39E behind which the lever may be en aged to hold it in one or other of its positions, as best shown in Said cam 3b is so formed when it isswung toward the rip handle 8 it will engage the stud 24 an will move the reciprocating member so that the roller stud 22 is not engageable by the cam 16. This permits the easy starting of the motor withoutload, aswitch trigger 40 in the handlecontrolling the supply of current by the motor. When the lever 37 is swung clockwise as in Fig. 2 to-engage behind the other shoulder 39 the stud is released from the influence of the cam 36 so that the roller stud 22 may again be acted upon by-the cam 16 on the shaft 14 to impart the return movement to the reciprocating member as before described after the motor is in operation.

My improved haer is light and balanced in weight and is capable of striking a powerful blow. it is simple in construction and the parts are easily assembled.

While in descrioing my invention l have referred in detail to certain forms and ar rangement of the parts thereof, ll do not wish to be limited thereto except as ay be pointed out in the appended claims.

I claim as my invention:

1. An electric beer of the hind described embodying therein a casing having an annular head and a barrel extension, said head being open at its front and rear end and having a middle partition wall, a motor closing the rear of the casing, a front plate closing the front of the casin means securing said motor, head and front plate together, a shaft journalled in said well and late and driven by the motor, a reciprocatmg member in said barrel extension, means connectin said shaft and reciprocating member or imparting a movement thereto in one direction, and a balance wheel fixed to said shaft adjacent the front plate.

2. An electric hammer embodying therein a casing, a reciprocating impact member having a sliding guiding bearing therein, a shaft and a motor for drivin means on said shaft for impartin a movement in one direction to said reciprocating member and means adapted to be enga ed with a part of said reciprocating mern er for removing it from the influence of said first mentioned means.

3. An electric hammer of the kind described embodying therein a casing having an annular head and a barrel extension, said head being open at its front and rear and motor, a reciprocating member with apart arranged in the barrel, guide plates on said partition in which said reciprocating" ber has sliding bearing, enacting on said shaft and member for reciprocating it in one direction and means adapted he I the same, I

eng I ed with a part of said I reciprocating in'sajd partition and plate and driven by the mem r for removing it from the influence motor, a reci rocatin member with a part of said coactin means,

4. An electric hammer of the kind described embodying thei'ein a casing havin an annular head and a barrel extens1o n,'sai head being open at its front and rear and having a middle partition, amotor closing one end of the casing and a plate closing the other end of the casing, a shaft journalled in said partition and plate and driven by the motor, a reel rocatin 7 arranged in t e barre means on said partition providing guiding bearing for said re ciprocating member, coacting means on said shaft and members for reciprocating it in one direction, and a levercam pivoted within said head and having a part projecting from said casing for manipulation, said lever cam being capable of actuation to engage apart of said reciprocating member to remove it from the influence of said coactin" means. 5. An electric hammer of the Eind described embodying therein a casing havin an annular head and a barrel extension, sai head being 0 n at its front and rear and having a mi dle'partition, a motor closing one end of the caslng and a plate closing the other end of the casing, a shaft journalled member in one direction,

member witha, part i arranged in t e barre means on said partition providing guiding bearing for said reciprocating member, coacting means on said shaft and member for reciprocating said a stud on said reciprocating member and a lever cam pivoted on said front late and adapted to be enaged with sai stud to remove said member roin the influence of said coacting means.

6. electric hammer of the kind described embodying therein a casing having an annular head and a barrel extension, said head ,bein open at its front and rear end, a motoric oslng one end of the casin and including an armature shaft, a plate 0 osing the other end of the casing, and in which said shaft is journalled, removable means for securing said motor, plate and easing head toget er, a reciprocating member in said barrel extension, means connecting said armature shaft and reciprocating member for imparting a movement thereto in one direction and a balance wheel fixed to said shaft adjacent said front plate.

In testimon whereof, I have hereunto set my hand, t is 21st day of A ril, 1927.

- JOHN KAfiCEVSK. 

